Deep Space Appears Closer to Us
And it is not because of the infamous “space expansion”, which has never happened!! Just by geometry, no gaslighting!!!
What happens with light emitted by distant galaxies a long time ago (when time in the Universe ran slower, as it was well explained in Time Matters), when our telescopes receive that light? As we discussed in Optical Effects of Time Variability, such light is redshifted. But besides that, refraction by Snell’s law plays an interesting role here!
With no time dilation accounted for, light from a star or a galaxy S is received at points O and C at straight, not deflected, lines of sight (SO) and (SC).
But in the past, time was slower than time nowadays, so starlight deflects by Snell’s law, with time dilation factor D playing a role of refractive index, and with incidence angle α changing to refraction angle β > α:
In comparison to the no-time-dilation scenario, distance |OC| has increased by factor D, and distance |AB| has remained the same. Light source image appears at S1, which is closer than S, where the light was emitted from:
Image of the galaxy appears smaller than its actual size. In optics, such effect is called “concave lensing”:
